Assessment of turbulence models for bubbly flows: Toward a five-equation turbulence model

Abstract

The paper presents an assessment of turbulence models in dispersed bubbly flows based on an analysis of their application to uniform and uniformly sheared homogeneous turbulence. This analysis leads to the development of a five-equation model where the total turbulent fluctuations in bubbly flow is submitted to a double decomposition: First, the turbulent fluctuations are split into Shear-Induced-Turbulence (SIT) and Bubble-Induced-Turbulence (BIT) components. Secondly, The BIT contribution is split into two components corresponding to non-dissipative pseudo-turbulent part and dissipative turbulent part produced by local shear in bubble’s wake. Consequently, the total turbulent energy is split into three contributions: two dissipative quantities kt and ks produced respectively by gradient of mean velocity in the liquid phase and by local shear in bubble’s wake both are described by their modeled transport equations as well as their dissipation rates εt and εs; and a non-dissipative component kp attributed to fluctuations of potential flow around bubbles described by its modeled transport equation. This model was implemented in CFD code and validated in homogeneous bubbly turbulence situations. The numerical results show a satisfactory agreement with experimental data of turbulence.